Currently, specifications of LTE-A (long term evolution-advanced) are considered by 3GPP (3rd Generation Partnership Project). Implementation of higher-speed LTE-A communication than LTE communication has been requested. For this reason, it has been decided that the LTE-A supports a wider band than used in LTE (beyond the LTE bandwidth of 20 MHz, up to the bandwidth of 100 MHz).
In LTE-A, for the purpose of maintaining the compatibility with LTE as much as possible, carrier aggregation (CA) technology is used. The carrier aggregation technology is a technology that uses a plurality of frequency bandwidths, each of which is up to 20 MHz and is called a component carrier (CC), performs collective communication, thus saving the bandwidth by up to 100 MHz and thereby implementing high speed communication with large capacity (see unit 5.5 of Non-Patent Document 1).
There are three CA methods based on the use of the frequency band to be used.
(1) Same contiguous frequency bands are used (Intra-band Contiguous CA).
(2) Same dispersed frequency bands are used (Intra-band Non-Contiguous CA).
(3) Different frequency bands are used (Inter-band Non-Contiguous CA).
The conventionally considered CA technology is CA technology among mobile stations and one macrocell base station, which has the feature that PUCCH (physical uplink control channel) is transmitted from the mobile station using only one CC. There are the following two reasons that it has been agreed that PUCCH be transmitted using one CC.                If PUCCH is transmitted using a plurality of CCs, PAPR and current consumption increase, and therefore the load on a battery of the mobile station device increases. For this reason, the PUCCH is transmitted using only one CC.        When the same contiguous frequency bands are used (the above (1)), the bands used for transmission of PUCCHs overlap one another, thus occasionally causing generation of spurious signals. For this reason, the PUCCH is transmitted using any one of the CCs.        
A CC used to transmit PUCCH is defined as a PCC (primary component carrier), and a CC not used to transmit PUCCH is defined as an SCC (secondary component carrier). Additionally, it has been agreed that an SCC is not used to transmit PRACH. In other words, the CA communication described here means a communication method in which a plurality of frequency bands are used to perform transmission and reception, but PUCCH is transmitted using only one CC.
Further, in the conventional multicarrier communication, in a case where a new frequency band is added, PRACH (physical random access channel) is transmitted using that frequency band to be added, synchronization is established, a connection process is performed, and thus the frequency band is added. PRACH signals also have been able to be used independently in any frequency bands.
The CA communication uses a different connection process from that used for the multi-carrier communication, and it is limited to a PCC, a first frequency band, that can use PRACH signals (see Section 7.5 of Non-Patent Document 1).